Method for manufacturing dials for watches and dials for watches manufactured according to said method

ABSTRACT

A glass watch dial is formed from a moldable glass batch comprising a mixture of glass-forming oxides, intermediate oxides, network-modifying oxides, and a devitrifying agent such as a metal oxide or a metal in colloidal dispersion, which is melted, and to which then is added a metal oxide capable of forming colored crystal nuclei of a synthetic mineral in the presence of the devitrifying agent, then the mass is cooled, the batch is molded to a dial and held at elevated temperature above its annealing point to permit the growth of crystallites from various minerals into the glass matrix to form a mineral similar in aspect, chemical composition and crystal structure to a semiprecious stone.

United States Patent [1 1 Simon-Vermot et al.

[451 Feb. 26, 1974 Hofer, both of Le Locle, Switzerland [73] Assignee:Les Fabriques dAssortiments Reunies, Neuchatel, Switzerland [22] Filed:Aug. 23, 1972 [2]] Appl. No.: 282,940

[52] U.S. Cl 58/91, 65/33, 65/60,

161/1, D42/1B [51 Int. Cl. G041! 39/00, C03b 29/00 [58] Field Of Search65/33, 60; 58/91; 161/1 [56] References Cited 1 UNITED STATES PATENTS3,275,492 9/1966 Herbert 65/33 X 3,528,828 9/1970 Smith 65/33 X3,117,881 1/1964 Henry et al. 65/33 X 3,146,114 8/1964 Kivlighn 65/33 X2,339,975 1/1944 Blau 65/33 X 3,157,522 11/1964 Stookey 65/33 X PrimaryExaminer-Frank W. Miga Attorney, Agent, or Firm-lmirie & Smiley 5 7]ABSTRACT A glass watch dial is formed from a moldable glass batchcomprising a mixture of glass-forming oxides, intermediate oxides,network-modifying oxides, and a devitrifying agent such as a metal oxideor a metal in colloidal dispersion, which is melted, and to which thenis added a metal oxide capable of forming colored crystal nuclei of asynthetic mineral in the presence of the devitrifying agent, then themass is cooled, the batch is molded to a dial and held at elevatedtemperature above its annealing point to permit the growth ofcrystallites from various minerals into the glass matrix to form amineral similar in aspect, chemical composition and crystal structure toa semiprecious stone.

8 Claims, 2 Drawing Figures METHOD FOR MANUFACTURING DIALS FOR WATCHESAND DIALS FOR WATCHES MANUFACTURED ACCORDING TO SAID METHOD BACKGROUNDOF THE INVENTION Watch dials made of semiprecious stones are well knownand used in high quality watches. Minerals or gems used for themanufacture of such dials are, for example, lapis lazuli, jade, onyx,jasper, opal, cats eye. In order to make dials, those minerals should becut, lapped and polished. Holes should be drilled and rounded. All ofthose operations need the use of expensive diamond tools. Therefore,since the price of the raw material is high and the machining difficult,those dials are expensive and their use is intended only for higherpriced jewelry watches.

SUMMARY OF THE INVENTION The present invention provides dials ofsynthetic semiprecious stone equally as gorgeous and as attractice asthose made of natural gems. Since the raw material is not expensive andthe machining shorter and easier this invention enables themanufacturing of attractive jewel watch dials at moderate cost.

In accordance with the present invention, there is provided a novelmethod for the manufacture of a semiprecious stone dial for watches orother types of timepieces, in which a glass body serves as the basicelement, but which provides in the resulting dial product, greatersturdiness and resistance to fracture than is the case with hithertoknown dials.

The process of the invention employs three basic ingredients for theproduction of the dial-forming glass body:

1. at least one glass-producing oxide which forms a glassy network orlattice;

2. intermediate and/or network-modifying oxides; and

3. devitrifying agent which is capable of forming synthetic mineralcrystal nuclei or particles in the glass matrix at elevated temperature.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view in perspective of ajewelry watch dial according to the invention, and

FIG. 2, is a fragmentary view in perspective of a modified jewelry watchdial.

DETAILED DESCRIPTION OF THE INVENTION Referring specifically to thedrawing, a jewelry dial according to the invention as shown in FIG. 1,comprises a molded or cast dial body 1 which is shown as a typicalcircular disc but may have any desirable configuration. The body may beformed with suitably located recesses, holes or apertures such as holes2 for anchoring individual hour indicia, a central bore 3 for the shaftscarrying the time indicating hands, a window 4 for displaying calendarindicia, and/or apertures 5 for anchoring a nameplate or the like. Theaforementioned openings may be formed during casting or molding, asdesired. Alternatively, as shown in FIG. 2, a dial 1' may have indicia2' formed in situ.

In carrying out the glass manufacturing operation, the different oxidesare first admixed with from about 1% to about by weight of thedevitrifying agent,

and the mixture is melted under controlled conditions at a temperaturebetween about 800 and about 1,400 C until a homogeneous molten mass isobtained. The coloring oxide is then added, and the mass is maintainedat a temperature in the range of about 800 C to about l,400 C. Byavoiding agitation, it is possible to obtain a diffusion of the addedmetal oxides into the interior of the glass, thus producing attractiveand ornamental flamed or branched patterns and other ornamental effectsvThereafter, the glass batch is cast and molded to form a dial of thedesired dimensions and shape. The molded dial is then slowly cooled to atemperature below the annealing point of the glass, i.e. until the glassshows a viscosity of about 10 poises. The molding may take place atordinary pressure or at increased pressure, up to several atmospheres.

As a part of the molding step, any desired passages, numeral indicia,sign feet, or signs in relief can be provided, as shown in the drawing.

After molding, the dial is slowly heated again to a temperature slightlyabove the annealing point of the glass, namely to about to 300 C abovethe annealing temperature and held at that temperature for about 10 to1,000 minutes. During this holding period, the growth of crystal nucleiand synthetic mineral particles is promoted. The dial is then allowedslowly to cool to avoid formation of fissures due to thermal shocks.

During this heat treatment, a devitrification of the glass is effected,imparting to the finished dial an aspect of a very fine, non-porous,colored ceramic. This ceramic may have uniform or flame typecolorations, depending on whether or not the coloring oxide has beenfinely admixed with the glass mass. Thus, if cobalt oxide has been usedas the coloring oxide, the dials may exhibit flame aspects varying fromlight blue to navy shades of color.

The presence of the devitrifying agent is believed to aid in theformation of crystal nuclei, which may be colored or not, depending uponthe kind of metal oxide present. The heat treatment to which the moldeddials are subjected, effects the growth of the crystals and theformation of synthetic semi-precious gems or minerals.

The basic glass material which forms a glassy lattice may be one or moreglass-producing inorganic oxides, such as, for example, silicon dioxideSiO boron trioxide B 0 or germanium oxide GeO The devitrifying agent maybe a metal oxide or a metal. Examples of suitable metal oxides are thosewhich provide good crystalline structure and refractory properties tothe glass body, including at least one of the following, TiO ZrO P 0 CrO M00 and W0 The devitrifying agent may also be a metal in colloidaldispersion, such as ruthenium, rhenium, palladium, osmium, platinum, andindium. The amount of devitrifying agent will be between about 1% and20% by weight of. the original glass-producing oxide. The metal oxidesmay be added either as such, or in the form of mineral raw materials,such as sand, feldspar,

and the like. The colloidal dispersion is produced by known procedures.

The metal oxide component of the glass dial compo sition is one which isknown to be an intermediate or modifier of the basic glass lattice. Suchmetal oxides include A1 0 Li O, Na O, K 0, BeO, MgO, CaO, ZnO, SrO, CdO,BaO, PbO, NiO, C00, FeO, MnO and 8110,.

Certain of these metal oxides impart to the glass composition a coloredshade, which enhances their omamental appearance. Some oxides arecapable of forming crystal nuclei of various minerals. Depending on thedesired aspect of the dial, it may be advantageous to add one or more ofthe coloring metal oxides to the completely melted mass of glass latticematerial and devitrifier.

The formation of crystal nuclei and minerals in the glass matrix willdepend upon the chemical composition of the starting material. However,X-ray diffraction methods indicate the presence of various crystallinephases, including such minerals as cordierite, rutile, crystallite,aluminum titanate, magnesium titanate, anorthite, anatase,beta-spodumene, mullite, betaeucryptite, tridymite, petalite, andquartz. These minerals impart to the finished dials an appearance verysimilar to that of dials manufactured from semiprecious stones anddestined for jewelry watches. Thus, the method of the invention can besaid to provide for the formation of synthetic semiprecious stones inthe glass mass. This is demonstrated by the fact that the appearance ofsuch phases as rutile, anorthite, anatase, petalite, tridymite andquartz is identical with that of the natural products.

The dials obtained by the method of the invention are non-porous, sturdyand much more resistant to fracture than those made of the parent,non-devitrified glass. They can be flame polished or diamond polished,and are readily processed by conventional methods.

The following examples illustrate specific products and ways in whichthe process can be carried out.

EXAMPLE 1 The oxides for producing semiprecious stone dials were weighedout in the following proportion:

wt percent ZnO 4.0 A1 8.0 SiO 72.0 2 2.5 K 0 1.5 L1 0 12.0

The materials are mixed together in a conventional manner as by a Vblender or pebble mill, then placed in a crucible and heated in a kilnup to l,300 C. At this temperature the glass is completely melted andthe coloring oxides can be added. CoO gives a blue color. A mixture inequal part of C00 and MnO gives a different blue. A blue green color isobtained in mixing CD203 and Co in different proportions. One part of Cro two parts of CuO and one part of C00 give an attractive green color.

Mixtures of Sb O FeO and SnO give gold colors of different shades. Cr Oand FeO provide brown colors, SnO CaO and Cr O give a pink color. Theweight percent of the added coloring oxides varies between 0.001 and 5%depending on the hue desired.

The crucible is kept in the kiln at the melting temperature for a timevarying between and 1,000 minutes, and the coloring oxides are more orless mixed depending on the artistic effect desired.

The dials are then cast in molds being the negative image of the dial,having protuberances or recesses for holes and signs in relief. Thedials are now slowly cooled and placed in an annealing furnace and keptat assembly in a watch or other timepiece.

EXAMPLE 2 were weighed out in the following proportions:

7 wt percent The oxides for producing semiprecious stone dials sio 55.0A1203 21.0 MgO 3.0 u o 6.0 ZnO 5.0 Tao 10.0

The processing is exactly the same as for Example 1 except that themelting temperature is higher (up to 1,400 C) and the annealingtemperature is 850 C. The same oxides are used for coloring the batch,the colors being somewhat different from Example 1 due to the differentbasic composition.

EXAMPLE 3 were weighed out in the following proportions:

wt perccnt SiO 60.0 A1 0; 12.0 TiO 14.0 Li O 6.0 MgO 4.0 CaO 4.0

The process is exactly the same as for Example 2.

EXAMPLE 4 The oxides for producing semiprecious stone dials were weighedout in the following proportions:

wt percent SiO, 40.0 A1 0 13.0 TD; 12.0 BaO 35.0

The oxides for producing semiprecious stone dials The process is thesame as for Example 1 except that the melting temperature is l,100 C andthe annealing temperature is 675 C. Coloring oxides were the same as forExample 1.

EXAMPLE 5 were weighed out in the following proportions:

wt percent SiO 18.0 A1 0 13.0 TiO l 1.0 PbO 58.0

The oxides for producing semiprecious stone dials The process and thetemperatures are the same as for Example 4.

EXAMPLE 6 The oxides for producing semiprecious stone dials were weighedout in the following proportions:

wt percent SiO 40.0 e a l 0.0 'l'lO 10.0 PbO 50.0

The process is the same as for Example 1, the melting temperature is1,000 C, and the annealing temperature is 650 C. The same oxides areused for coloring the batch, the colors being somewhat different fromExample 1 due to the different basic composition.

EXAMPLE 7 The oxides for producing semiprecious stone dials were weighedout in the following proportions:

wt percent so, 5.0 2 3 15.0 ZnO 16.0 PhO 64.0

The process is the same as for Example 1, the melting temperature is 950C, and the annealing temperature is 600 C. The same oxides are used forcoloring the batch, the colors being somewhat different from Example 1due to the different basic composition.

EXAMPLE 8 The oxides for producing semiprecious stone dials were weighedout in the following proportions:

wt percent A1 0 14.0 2 63.0 CaO 16.0 TiO 7.0

The process is the same as for Example 1, the melting temperature is 900C, and the annealing temperature is 575 C. The same oxides were used forcoloring the batch, the colors being somewhat different from Example 1due to the different basic composition.

What is claimed is:

1. Method for the manufacture of molded glass timepiece dials,comprising the steps of:

a. forming a homogeneous molten glass body by melting a mixture of atleast one glass-latticeforming glass-producing oxide and from about 1%to about 20% by weight of a devitrifying agent capable of formingsynthetic mineral crystal nuclei or particles in the glass matrix atelevated temperature; b. adding to said glass body at a temperature inthe range of about 800 C to about 1,400 C an amount of at least onenetwork-modifying metal oxide capable of modifying the glass lattice byforming synthetic mineral crystal particles in the glass matrix at atemperature above the stabilization point of the glass body, andmaintaining the molten mass in said temperature range without agitationto obtain diffusion of the added metal oxide into the interior of theglass so as to produce flamed or branched patterns or other ornamentaleffects therein;

c. molding the glass body to form a dial including openings, passages,or indicia therein;

(1. heating the molded dial to a temperature slightly above thestabilization or annealing point of the glass for a period of timesufficient to permit the devitrification of the glass and the growth inthe glass body of crystal nuclei of a synthetic mineral from said metaloxide; and

e. slowly cooling the molded dial to avoid the formation of fissures dueto thermal shock.

2. The method of claim 1 in which the glassproducing oxide is selectedfrom the group consisting of silicon dioxide, boron trioxide, phosphoruspentoxide, and germanium dioxide.

3. The method of claim 1 in which the devitrifying agent is selectedfrom the group consisting of titanium dioxide, zirconium dioxide,phosphorus pentoxide, chromium oxide, molybdenum trioxide, and tungstentrioxide.

4. The method of claim 1 in which the devitrifying agent is a colloidaldispersion of at least one metal selected from the group consisting ofplatinum, ruthenium, rhenium, palladium, osmium, and indium.

5. The method of claim 1 in which the networkmodifying metal oxide is atleast one member selected from the group consisting of aluminum oxide,lithium oxide, sodium oxide, potassium oxide, beryllium oxide, magnesiumoxide, calcium oxide, zinc oxide, strontium oxide, cadmium oxide, bariumoxide, lead monoxide, nickel oxide, cobalt oxide, ferric oxide, tindioxide and manganese oxide.

6. The method of claim 1 in which the heat treatment of step (d) iscarried out at a temperature about 100 to about 300 C above thestabilization point of the glass for a period of about 10 to 1,000minutes.

7. The method of claim 1 in which the synthetic mineral formed is atleast one member selected from the group consisting of cordierite,rutile, crystallit'e, aluminum titanate, magnesium titanate, anorthite,anatase, beta-spodumene, mullite, beta-eucryptite, tridymit'e, petaliteand quartz.

8. A dial for timepieces and the like comprising a molded body of aglass prepared in accordance with the method of claim 1.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 193 2Dated m 2 5 m2 Icventofls) It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

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cantonmm- 1; Switzerland 1 Signed arid sealed this 15th day of October1974.

(SEAL) Attest:

, McCOY M.YGIB SON JR; c. MARSHALL DANN Attesting Officer Commissionerof Patents v uscoMM-oc scam-pas v.5 GOVERNMENT PRINTING OHICI: I.0-386-334 I I Patent No. 3 293 32 Dated Inventor(s) It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

IN THE HEADYNG:

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Canton-of Nouchitol, Switzerland- Signed and sealed this 15th day ofOctober 1974.

(SEAL) Attest:

. McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents USCOMM-DC 60375-1 69 1? 0.8 GOVERNMENT PRINTING OFFICE 15690-365-334 I XOR! PO-105O (10-69)

2. The method of claim 1 in which the glass-producing oxide is selectedfrom the group consisting of silicon dioxide, boron trioxide, phosphoruspentoxide, and germanium dioxide.
 3. The method of claim 1 in which thedevitrifying agent is selected from the group consisting of titaniumdioxide, zirconium dioxide, phosphorus pentoxide, chromium oxide,molybdenum trioxide, and tungsten trioxide.
 4. The method of claim 1 inwhich the devitrifying agent is a colloidal dispersion of at least onemetal selected from the group consisting of platinum, ruthenium,rhenium, palladium, osmium, and indium.
 5. The method of claim 1 inwhich the network-modifying metal oxide is at least one member selectedfrom the group consisting of aluminum oxide, lithium oxide, sodiumoxide, potassium oxide, beryllium oxide, magnesium oxide, calcium oxide,zinc oxide, strontium oxide, cadmium oxide, barium oxide, lead monoxide,nickel oxide, cobalt oxide, ferric oxide, tin dioxide and manganeseoxide.
 6. The method of claim 1 in which the heat treatment of step (d)is carried out at a temperature about 100* to about 300* C above thestabilization point of the glass for a period of about 10 to 1,000minutes.
 7. The method of claim 1 in which the synthetic mineral formedis at least one member selected from the group consisting of cordierite,rutile, crystallite, aluminum titanate, magnesium titanate, anorthite,anatase, beta-spodumene, mullite, beta-eucryptite, tridymite, petaliteand quartz.
 8. A dial for timepieces and the like comprising a moldedbody of a glass prepared in accordance with the method of claim 1.